5 Answers
5

"Standard of Proof" or "Burden of Proof" is a scientific or legal phrase explaining how much evidence you need before you can "legitimately" assert that something is true.

The author is saying that many people studying human behavior are much more tolerant to accepting things that are obvious than people studying something that was considered an "exact science".

One could reword the sentence:

Many people interested in human behavior do not feel the need for as much proof or evidence as it would take to prove something in an exact science like physics or chemistry; they feel the uniformities in behavior are "obvious" without all that rigor.

I understand it to intend for proof to mean, roughly, evidence. By standards of proof, the author is probably referring to tools of scientific analysis, like statistics or laboratory-controlled studies.

The claim that the author is making is that there are people who think that human behavior should not be studied by using these tools (that are widely used in the other sciences). Such people feel that the conclusions that they are able to draw (about human behavior), simply by using observation and intuition, are sufficiently rigorous and valid. The author's tone suggests that he disagrees with those people.

Many people do not believe that human behavior is an exact science, and therefore they do not feel that the standards of proof that are associated with an exact science need to be met when proving something about human behavior.

A "standard of proof" is a minimum level of quality that a proof must meet in order to be considered valid.

An example of such a standard would be, in physics, that an experiment must reliably and repeatedly produce identical results when set up and run by different experimenters; whereas in a study of human behavior, two identical experiments that produce "roughly similar" results may be considered good enough.

"Proof" is a noun here, meaning "evidence sufficient to justify accepting something as true". So "standards of proof" means the amount and strength of the evidence we have to have to consider that evidence to constitute proof.

An "exact science" is one in which measurements are quantified, that is, expressed numerically. So, for example, claims in physics aren't that something will travel "fast" or need "a lot" of energy. They involve calculating specific speeds and amounts.

The author is talking about whether human behavior should be studied using the methods of an exact science.